Coacervation of cationic gemini surfactant with N-benzoylglutamic acid in aqueous solution
Coacervation of cationic gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) with pH-sensitive N-benzoylglutamic acid (H2Bzglu) has been investigated by potentiometric pH-titration, turbidity titration, dynamic light scattering (DLS), isothermal titration calorimetry (...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1992. - 29(2013), 48 vom: 03. Dez., Seite 14839-47 |
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| 1. Verfasser: | |
| Weitere Verfasser: | , , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2013
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article Research Support, Non-U.S. Gov't Alkenes Cations Glutamates Quaternary Ammonium Compounds Solutions Surface-Active Agents hexamethylene-1,6-bis(dodecyldimethylammonium bromide) Water mehr... |
| Zusammenfassung: | Coacervation of cationic gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) with pH-sensitive N-benzoylglutamic acid (H2Bzglu) has been investigated by potentiometric pH-titration, turbidity titration, dynamic light scattering (DLS), isothermal titration calorimetry (ITC), TEM, (1)H NMR, and light microscopy. Phase boundaries of the 12-6-12/H2Bzglu mixture were obtained over the pH range from 2 to 9 and in the H2Bzglu concentration range from 30.0 to 50.0 mM at pH 4.5. When the H2Bzglu concentration is beyond 30.0 mM, the 12-6-12/H2Bzglu mixed solution undergoes the phase transitions from soluble aggregate, to precipitate, coacervate, and soluble aggregate again as pH increases. The results indicate that coacervation occurs at extremely low 12-6-12 concentration and lasts over a wide surfactant range, and can be enhanced or suppressed by changing pH, 12-6-12/H2Bzglu molar ratio and H2Bzglu concentration. The coacervates present a disorderly connected lay structure. Coacervation only takes place at pH 4-5, where the aggregates are nearly charge neutralized, and a minimum H2Bzglu concentration of 30.0 mM is required for coacervation. In this pH range, H2Bzglu mainly exist as HBzglu(-). The investigations on intermolecular interactions indicate that the aggregation of 12-6-12 is greatly promoted by the strong electrostatic and hydrophobic interactions with the HBzglu(-) molecules, and the interaction also promotes the formation of dimers, trimers, and tetramers of HBzglu(-) through hydrogen bonds. The double chains of 12-6-12 and the HBzglu(-) oligomers can play the bridging roles connecting aggregates. These factors endow the mixed system with a very high efficiency in generating coacervation |
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| Beschreibung: | Date Completed 25.09.2014 Date Revised 11.12.2018 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1520-5827 |
| DOI: | 10.1021/la403582y |